1) Field of the Invention
The present invention relates to a quantum tunneling transistor. More particularly, but not by way of limitation, the present invention relates to a three pin quantum tunneling transistor which may be readily substituted for prior art devices such as transistors, MOSFETs, IGBTs, and the like.
2) Background of the Invention
While the development of quantum tunneling transistors has been ongoing for several years, it is only recently that great strides have been made towards achieving a device practical for every day applications. Unfortunately, the quantum tunneling transistors which show the greatest promise for use in practical applications also require complex switching schemes and are thus not readily adapted to present designs.
Generally speaking, the term xe2x80x9cquantum tunnelingxe2x80x9d is used to describe a phenomenon wherein electrons cross a dielectric boundary based on a probability model, despite the fact that, in theory, electrical current should not flow through the insulator. It is accepted that tunneling electrons behave like a wave, rather than a particle. The quantum tunneling effect has shown great promise in a number of electronic components such as varistors and diodes, as well as transistor devices. Important features of such devices are, by way of example and not limitation: dramatic improvement in switching speeds over prior art devices; negative resistance in transitioning from the off state to the on state; exceptionally low on resistance; good consistency between parts; etc. As will be apparent to those skilled in the art, these properties make the quantum tunneling transistor particularly well suited to a variety of relatively high power applications such as radio frequency circuitry and DC motor controls.
It should be noted that, at least to some degree, quantum tunneling devices, whether transistor or varistor devices, are operated at a voltage sufficient to cause tunneling, but below a voltage which causes breakdown of the dielectric. It will thus be apparent to those skilled in the art that the selection of the insulating material, or layer, is crucial to operation of the device in that it must exhibit a dielectric strength sufficient to avoid breakdown during normal operation of the device.
It should be mentioned too, that much of the development of quantum tunneling transistors appears to be centered about the use of such devices in highly integrated circuitry (i.e., microprocessors, memory device, and the like). As should be apparent to those skilled in the art, quantum tunneling transistors also exhibit properties which are particularly well suited for use in moderate to high power applications. In particular, low on-resistance and exceptionally fast switching speeds make these devices attractive for use in RF and motor control applications. Unfortunately, the topology favored for use in integrated circuits is not particularly well suited for use in power switching circuits.
Presently this has resulted in the appearance of devices which, on the one hand, use unconventional means to control the gate, or base, input of the device, such as light (using photons to initiate tunneling) or mechanical vibration and, on the other hand, devices which require multiple voltages at multiple gate inputs (sometimes referred to as 5-pin devices) to initiate tunneling. Neither method is well suited to adapting presently designed equipment for use with quantum tunneling transistors.
It is thus an object of the present invention to provide a quantum tunneling transistor which is adapted to operate in a manner similar to a bipolar transistor, MOSFET, IGBT, or the like.
It is still a further object of the present invention to provide a variety of circuits wherein the particular features of the quantum tunneling transistor produce surprising and unexpected improvements in such circuits.
The present invention provides a quantum tunneling transistor which provides two switching inputs (for example, source and drain as with a conventional FET) and a control input which, in one embodiment, performs much like the gate input of a conventional FET. In one embodiment, circuitry is integrated onto the semiconductor substrate material of the transistor to provide a plurality of switching voltages to the transistor. The circuitry is configured such that switching of the transistor is controlled by a single, high impedance input, thus allowing the use of the quantum tunneling transistor in existing applications.
In another embodiment, a quantum tunneling transistor, such as the device described above, is used to directly drive a resonant circuit coupled to an antenna to provide a single transistor, high power RF power amplifier.
In yet another preferred embodiment, a quantum tunneling transistor, such as the device described above, is incorporated into a DC motor controller. The fast transition times and low on-state resistance of the quantum tunneling transistor provide an unexpected cost reduction, allowing the use of notably smaller heat sinks and simpler drive circuitry than was allowed with prior art devices.
In still another embodiment, a quantum tunneling transistor, such as the device described above, is incorporated into an integrated circuit. Of particular interest is the three-pin nature of the inventive device which allows its use as a xe2x80x9cdrop-inxe2x80x9d replacement in existing circuit designs.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.